﻿package com.sbox.util;

import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

public class SimpleCrypto 
{
	public static String encrypt(String seed, String cleartext) throws Exception {      
            byte[] rawKey = getRawKey(seed.getBytes());      
            byte[] result = encrypt(rawKey, cleartext.getBytes());      
            return toHex(result);      
        }      
              
        public static String decrypt(String seed, String encrypted)  throws Exception{      
            byte[] rawKey = getRawKey(seed.getBytes());      
            byte[] enc = toByte(encrypted);      
            byte[] result = decrypt(rawKey, enc);      
            return new String(result);      
        }      
         
        private static byte[] getRawKey(byte[] seed)  throws Exception{      
            KeyGenerator kgen = KeyGenerator.getInstance("AES");      
            SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");      
            sr.setSeed(seed);      
            kgen.init(128, sr); // 192 and 256 bits may not be available       
            SecretKey skey = kgen.generateKey();      
            byte[] raw = skey.getEncoded();      
            return raw;      
        }      
         
              
        private static byte[] encrypt(byte[] raw, byte[] clear)  throws Exception {      
            SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");      
            Cipher cipher = Cipher.getInstance("AES");      
            cipher.init(Cipher.ENCRYPT_MODE, skeySpec);      
            byte[] encrypted = cipher.doFinal(clear);      
            return encrypted;      
        }      
         
        private static byte[] decrypt(byte[] raw, byte[] encrypted)  throws Exception {      
            SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");      
            Cipher cipher = Cipher.getInstance("AES");      
            cipher.init(Cipher.DECRYPT_MODE, skeySpec);      
            byte[] decrypted = cipher.doFinal(encrypted);      
            return decrypted;      
        }      
         
        public static String toHex(String txt) {      
            return toHex(txt.getBytes());      
        }      
        public static String fromHex(String hex) {      
            return new String(toByte(hex));      
        }      
              
        public static byte[] toByte(String hexString) {      
            int len = hexString.length()/2;      
            byte[] result = new byte[len];      
            for (int i = 0; i < len; i++)      
                result[i] = Integer.valueOf(hexString.substring(2*i, 2*i+2), 16).byteValue();      
            return result;      
        }      
         
        public static String toHex(byte[] buf) {      
            if (buf == null)      
                return "";      
            StringBuffer result = new StringBuffer(2*buf.length);      
            for (int i = 0; i < buf.length; i++) {      
                appendHex(result, buf[i]);      
            }      
            return result.toString();      
        }      
        private final static String HEX = "0123456789ABCDEF";      
        private static void appendHex(StringBuffer sb, byte b) {      
            sb.append(HEX.charAt((b>>4)&0x0f)).append(HEX.charAt(b&0x0f));      
        }   
}